The now fully ported intake runner is limited only by the need to retain adequate material
What's It Gonna Cost Me?
That could be a $1,000 question, if you go the fully ported route. On the low-end, you're looking at around $200 for a professional three-angle valve job with the existing 1.94/1.50 valves. Add bowl-porting and a set of big valves and you move up into the $500-$700 range. In terms of performance returned for this investment, the accompanying Price Vs. Performance graph is instructive. It compares the combined maximum intake and exhaust flow observed at each modification stage with the typical cost of those modifications. The data points with locations highest and farthest to the right represent the most return-per-dollar invested.
Also included on the chart are four popular aftermarket 23-degree valve-angle heads: GM's late-model 350 "Vortec" LT1 head, Dart's new "Iron Eagle" head, and two Air Flow Research aluminum heads. The combined flow data is taken from our sister publication Chevy High Performance's recent extensive flow tests of popular aftermarket heads, and represents their as-delivered, out-of-the-box configuration. The purchase cost of used 041 heads is not included because we assume you already have a set of stock heads. Pricing for both the 041 heads and the Vortec heads does not include valvesprings or ancillary components. The other aftermarket heads are quoted as complete assemblies.
Overall exhaust port volume isn't as important as its overall geometrical shape. Every por
This scatter-chart reveals several interesting trends. If all you want is a valve job, brand-new GM Vortec heads are a better choice than reusing old heads, delivering more performance for only $100 more. The chart's "sweet spot" (the best balance between performance and cost) is occupied by the 041's valve job, bowl, and short-side porting modification stage. Out-of-the-box Dart Iron Eagle heads are price competitive with fully ported 1.94/1.50 valve 041 heads. Fully porting the 041 heads with the big valves installed offers a better cost/benefit ratio than the high-zoot AFR heads, but the 041 iron units are much heavier and more detonation prone than the AFR aluminum heads. Of course, fully porting any of these aftermarket heads to the same level as our 041s would yield considerably greater performance gains, but the costs could easily double. There's no such thing as a free lunch.
GT Alley Performance
515 W.Allen Ace., Ste. 15